What is the name for the pair of forces that occur when one object pushes on another and the second pushes back with equal magnitude in the opposite direction?

• A. Normal Force
• B. Action-Reaction Pair
• C. Buoyant Force
• D. Gravitational Potential Energy

Answer: (B)

When two objects push on each other, the forces involved have equal strength and opposite directions. This is Newton’s third law in action: for every action force, there is an equal and opposite reaction force, and they act on different objects at the same time. The name for this paired interaction is the action-reaction pair.

For example, pushing on a wall: your hand exerts a force on the wall, and the wall exerts an equal and opposite force on your hand.

Normal force is the contact force a surface exerts on an object, buoyant force is the fluid’s push on an immersed object, and gravitational potential energy is a form of energy, not a force. The correct term for the pair of forces is the action-reaction pair.